Genome could unlock eucalyptus potential for paper, fuel and fiber

CORVALLIS, Ore. – In a collaboration spanning five continents, scientists have announced the complete sequencing of one of the world’s most widely planted trees, Eucalyptus grandis.

Used for fuel and timber, the species is valued for fast growth and straight grain. Grown usually as a hybrid, it is one of more than 500 species of eucalyptus trees and shrubs that provide a renewable source of fiber, pulp, biofuel material, and medicinal and industrial oils. The accomplishment was published today in the scientific journal Nature.

On the research team were 12 Oregon State University scientists, including plant biologist Pankaj Jaiswal. "This genome sequence will help usher in a new era for studying the biology of the eucalyptus tree. Our advances in understanding could help redefine the possibilities of improving biomass yield, stress tolerance and other traits," said Jaiswal, a botany and plant pathology professor in OSU's College of Agricultural Sciences.

Jaiswal and his colleagues used the high-performance computing facility in Oregon State’s Center for Genome Research and Biocomputing to assign functions to the tree's 36,000-plus genes. They identified which genes correspond to biological processes that underpin control of growth rate, wood hardness, flowering and other attributes.

Plant breeders can use the eucalyptus genome to enhance or suppress traits in the tree, Jaiswal added. For example, breeding for more lignin, which confers strength to woody tissue, can produce wood better suited for furniture. Trees with less lignin could require less energy and fewer chemicals needed to make paper from eucalyptus pulp.

For breeding purposes, one of the most significant accomplishments stems from understanding the genes associated with flowering. Eucalyptus trees generally take three to 10 years to flower after they are propagated from seed, a process that slows the rate of breeding considerably, said Steve Strauss, a co-author of the Nature paper and an Oregon State distinguished professor of forest biotechnology in the College of Forestry.

Strauss has already shown that activating genes responsible for flower development can accelerate flowering. "By accelerating the speed of eucalyptus flowering, plant breeders can shorten generation time for developing new varieties with improved traits," he said.

Researchers can also use the floral gene sequences to prevent or disrupt flowering. That technology could help stop the undesirable spread of the tree and prevent it from becoming invasive.

The study is also leading to a better understanding of the evolutionary relationships of eucalyptus and its relatives. OSU professors Joseph Spatafora and Aaron Liston worked with Jaiswal to redefine the placement of eucalyptus in plant classification. "We managed to reassign its position in the evolutionary tree of life," said Liston.

“The genome provides a better roadmap for breeders to follow, although there is still a long road ahead of us to adapt the plant to all of our desired uses,” he added.

A research group from South Africa, led by Alexander Myburg of the Forestry and Agricultural Biotechnology Institute at the University of Pretoria, supplied the eucalyptus tissues and RNA sequenced by Oregon State.

Collaborating in the research were 80 scientists in South Africa, Brazil, North America, Europe and Australia (where eucalyptus originated). Among the funding sources were Oregon State University, the Tree Biosafety and Genomics Research Cooperative and the National Science Foundation. A contribution by the U.S. Department of Energy Joint Genome Institute was supported by the DOE Office of Science.

Other OSU researchers contributing to the project were: Sushma Naithani, Justin Elser, Rajani Raja and Palitha Dharmawardhana in the Department of Botany and Plant Pathology in the College of Agricultural Sciences; Martin Ranik, Vindhya Amarasinghe and Kelly Vining in the College of Forestry; Alexander E. Boyd and Christopher Sullivan in the Center for Genome Research and Biocomputing.